Los Angeles Against the Mountains—I

In “Los Angeles Against the Mountains,” a 1988 installment in the New Yorker series “The Control of Nature,” which was later published as a book, John McPhee described how Southern California’s dry chaparral produces devastating fires.

Evergreen oaks were fingering up the creases in the mountainsides, pointing toward the ridgeline forests of bigcone Douglas fir, of knobcone and Coulter pine. The forests had an odd sort of timberline. They went down to it rather than up. Down from the ridges the conifers descended through nine thousand, seven thousand, six thousand feet, stopping roughly at five. The forests abruptly ended—the country below being too dry in summer to sustain tall trees. On down the slopes and all the way to the canyons was a thicket of varied shrubs that changed in character as altitude fell but was everywhere dense enough to stop an army. On its lower levels, it was all green, white, and yellow with buckwheat, burroweed, lotus and sage, deerweed, bindweed, yerba santa. There were wild morning glories, Canterbury bells, tree tobacco, miner’s lettuce. The thicket’s resistance to trespass, while everywhere formidable, stiffened considerably as it evolved upward. There were intertwining mixtures of manzanita, California lilac, scrub oak, chamise. There was buckthorn. There was mountain mahogany. Generally evergreen, the dark slopes were splashed here and there with dodder, its mustard color deepening to rust. Blossoms of the Spanish bayonet stood up like yellow flames. There were lemonade berries (relatives of poison ivy and poison oak). In canyons, there were alders, big-leaf-maple bushes, pug sycamores, and California bay. Whatever and wherever they were, these plants were prickly, thick, and dry, and a good deal tougher than tundra. Those evergreen oaks fingering up the creases in the mountains were known to the Spaniards as chaparros. Riders who worked in the related landscape wore leather overalls open at the back, and called them chaparajos. By extension, this all but impenetrable brush was known as chaparral.

The low stuff, at the buckwheat level, is often called soft chaparral. Up in the tough chamise, closer to the lofty timber, is high chaparral, which is also called hard chaparral. High or low—hard, soft, or mixed—all chaparral has in common an always developing, relentlessly intensifying, vital necessity to burst into flame. In a sense, chaparral consumes fire no less than fire consumes chaparral. Fire nourishes and rejuvenates the plants. There are seeds that fall into the soil, stay there indefinitely, and will not germinate except in the aftermath of fire. There are basal buds that sprout only after fire. Droughts are so long, rains so brief, that dead bits of wood and leaves scarcely decay. Instead, they accumulate, thicken, until the plant community is all but strangling in its own duff. The nutrients in the dead material are being withheld from the soil. When fire comes, it puts the nutrients back in the ground. It clears the terrain for fresh growth. When chaparral has not been burned for thirty years, about half the thicket will be dry dead stuff—twenty-five thousand tons of it in one square mile. The living plants are no less flammable. The chamise, the manzanita—in fact, most chaparral plants—are full of solvent extractives that burn intensely and ignite easily. Their leaves are glossy with oils and resins that seal in moisture during hot dry periods and serve the dual purpose of responding explosively to flame. In the long dry season, and particularly in the fall, air flows southwest toward Los Angeles from the Colorado Plateau and the Basin and Range. Extremely low in moisture, it comes out of the canyon lands and crosses the Mojave Desert. As it drops in altitude, it compresses, becoming even dryer and hotter. It advances in gusts. This is the wind that is sometimes called the foehn. The fire wind. The devil wind. In Los Angeles, it is known as Santa Ana. When chamise and other chaparral plants sense the presence of Santa Ana winds, their level of moisture drops, and they become even more flammable than they were before. The Santa Anas bring what has been described as “instant critical fire weather.” Temperatures rise above a hundred degrees. Humidity drops very close to zero. According to Charles Colver, of the United States Forest Service, “moisture evaporates off your eyeballs so fast you have to keep blinking.”

Ignitions are for the most part caused by people—through accident or arson. Ten per cent are lightning. Where the Santa Anas collide with local mountain winds, they become so erratic that they can scatter a fire in big flying brands for a long distance in any direction. The frequency and the intensity of the forest fires in the Southern California chaparral are the greatest in the United States, with the possible exception of the wildfires of the New Jersey Pine Barrens. The chaparral fires are considerably more potent than the forest fires Wade Wells saw when he was an undergraduate at the University of Idaho or when he worked as a firefighter in the Pacific Northwest. “Fires in the Pacific Northwest are nothing compared with these chaparral fires,” he remarked. “Chaparral fires are almost vicious by comparison. They’re so intense. Chaparral is one of the most flammable vegetation complexes there are.”

It burns as if it were soaked with gasoline. Chaparral plants typically have multiple stems emerging from a single root crown, and this contributes not only to the density of the thickets but, ultimately, to the surface area of combustible material that stands prepared for flame. Hundreds of acres can be burned clean in minutes. In thick black smoke there is wild orange flame, rising through the canyons like explosion crowns. The canyons serve as chimneys, and in minutes whole mountains are aflame, resembling volcanoes, emitting high columns of fire and smoke. The smoke can rise twenty thousand feet. A force of two thousand people may fight the fire, plus dozens of machines, including squadrons in the air. But Santa Ana firestorms are so violent that they are really beyond all effort at control. From the edge of the city upward, sixteen miles of mountain front have burned to the ridgeline in a single day.

So momentous are these conflagrations that they are long remembered by name: the Canyon Inn Fire, August, 1968, nineteen thousand acres above Arby’s by Foothill Boulevard, above the world’s foremost container nursery, above the chief executive officer of Mackinac Island Fudge; the Village Fire and the Mill Fire, November, 1975, sixty-five thousand acres above Sunland, Tujunga, La Crescenta, La Cañada. The Mill Fire, in the words of a foreman at Flood, “burnt the whole front face off.”

It is not a great rarity to pick up the Los Angeles Times and see a headline like this one, from September 27, 1970:

In millennia before Los Angeles settled its plain, the chaparral burned every thirty years or so, as the chaparral does now. The burns of prehistory, in their natural mosaic, were smaller than the ones today. With cleared fire lanes, chemical retardants, and other means of suppressing what is not beyond control, people have conserved fuel in large acreages. When the inevitable fires come, they burn hotter, higher, faster than they ever did in a state of unhindered nature. ♦